Directory Structure
final effect
Implementation code
MyData.java
package Data_Time;
/**
* @ClassName MyData
* @Description ：TODO
* @Author Josvin
* @Date 2021/01/24/14:58
*/
/**
* 构造方法：
* MyDate(MyDate date);
* MyDate(int year, int month, int day);
*
* 对方方法:
* public void next(); // 让日期往后走一天
* public void previous(); // 让日期往前走一天
*
* public String toString(); // 返回日期的字符串表示形式 年-月-日
*/
public class MyData {
private int year;
private int month;
private int day;
public MyData(MyData date) {
this.year = date.year;
this.month = date.month;
this.day = date.day;
}
public MyData(int year, int month, int day) {
check(year, month, day);
// 代码可以运行到这个位置，说明方法内部没有抛异常
// 所以参数是合法的
this.year = year;
this.month = month;
this.day = day;
}
@Override
public String toString() {
return String.format("%d-%02d-%02d", year, month, day);
}
// 日期向后走一天
public void next() {
day++;
if (day <= getDayOfMonth(year, month)) {
return;
}
month++;
day = 1;
if (month <= 12) {
return;
}
year++;
month = 1;
}
// 日期向前走一天
public void previous() {
day--;
if (day >= 1) {
return;
}
month--;
if (month >= 1) {
day = getDayOfMonth(year, month); // 必须先对 month--，再计算有多少天
return;
}
year--;
month = 12;
day = getDayOfMonth(year, month);
}
private static void check(int year, int month, int day) {
if (month < 1 || month > 12) {
throw new RuntimeException("month 的有效范围是 [1, 12]");
}
int days = getDayOfMonth(year, month);
if (day < 1 || day > days) {
throw new RuntimeException("day 的有效范围是 [1, " + days + "]");
}
}
private static final int[] DAYS = {
31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
private static int getDayOfMonth(int year, int month) {
if (month == 2 && isLeapYear(year)) {
return 29;
}
return DAYS[month - 1];
}
private static boolean isLeapYear(int year) {
return year % 400 == 0 || (year % 4 == 0 && year % 100 != 0);
}
}
MyTime.java
package Data_Time;
/**
* @ClassName MyTime
* @Description ：TODO
* @Author Josvin
* @Date 2021/01/24/15:00
*/
public class MyTime {
private int hour;
private int minute;
private int second;
public MyTime(MyTime time) {
this.hour = time.hour;
this.minute = time.minute;
this.second = time.second;
}
public MyTime(int hour, int minute, int second) {
check(hour, minute, second);
this.hour = hour;
this.minute = minute;
this.second = second;
}
// 返回值代表本次 Time 向后走一秒，是否走到第二天
// true：有进位
// false：没有进位
public boolean next() {
second++;
if (second < 60) {
return false;
}
minute++;
second = 0;
if (minute < 60) {
return false;
}
hour++;
minute = 0;
if (hour < 24) {
return false;
}
hour = 0;
return true;
}
public boolean previous() {
second--;
if (second >= 0) {
return false;
}
minute--;
second = 59;
if (minute >= 0) {
return false;
}
hour--;
minute = 59;
if (hour >= 0) {
return false;
}
hour = 23;
return true;
}
@Override
public String toString() {
return String.format("%02d:%02d:%02d", hour, minute, second);
}
private static void check(int hour, int minute, int second) {
if (hour < 0 || hour >= 24) {
throw new RuntimeException("hour 的有效范围是 [0, 23]");
}
if (minute < 0 || minute >= 60) {
throw new RuntimeException("minute 的有效范围 [0, 59]");
}
if (second < 0 || second >= 60) {
throw new RuntimeException("second 的有效范围是 [0, 59]");
}
}
}
MyDateTime.java
package Data_Time;
/**
* @ClassName MyDateTime
* @Description ：TODO
* @Author Josvin
* @Date 2021/01/24/15:12
*/
// 既有年月日，又有时分秒
public class MyDateTime {
// private int year;
// private int month;
// private int day;
private MyData date;
// private int hour;
// private int minute;
// private int second;
private MyTime time;
public MyDateTime(MyDateTime datetime) {
this.date = datetime.date; // TODO: BUG fix
this.time = datetime.time; /* // TODO: BUG fix*/
/*this.date = new MyData(datetime.date);
this.time = new MyTime(datetime.time);
*/
}
public MyDateTime(int year, int month, int day, int hour, int minute, int second) {
this.date = new MyData(year, month, day);
this.time = new MyTime(hour, minute, second);
}
// 部分构造，只传年月日，时分秒默认设置成 0时0分0秒
public MyDateTime(int year, int month, int day) {
this(year, month, day, 0, 0, 0);
}
public MyDateTime(MyData date) {
this.date = date; // TODO: BUG fix
// this.date = new MyData(date);
this.time = new MyTime(0, 0, 0);
}
// 向后走一秒
public void next() {
if (time.next()) {
date.next();
}
}
// 向前走一秒
public void previous() {
if (time.previous()) {
date.previous();
}
}
@Override
public String toString() {
return String.format("%s %s", date, time);
}
}
Test11.java
package Data_Time; /**
* @ClassName Data_Time.Test11
* @Description ：TODO
* @Author Josvin
* @Date 2021/01/24/15:16
*/
import java.util.concurrent.TimeUnit;
public class Test11 {
public static void main(String[] args) throws InterruptedException {
MyDateTime datetime = new MyDateTime(2021, 1, 31, 23, 59, 53);
MyDateTime datetime2 = new MyDateTime(datetime);
/*
datetime.next();
datetime.next();
System.out.println(datetime);
System.out.println(datetime2);
*/
while (true) {
System.out.println(datetime);
datetime.next();
TimeUnit.SECONDS.sleep(1);
}
}
}
But there is a problem here:
if you execute this code and
output the same result here, there is a problem. The main problem is still here, because two objects operate on the same content.
And we should operate different content because there should be two parts:
after modification:
we will run Test11 again and the
operation is not the same piece of content, so dt2 is unchanged.